1. Field of Invention
Utilization of metal chips, especially scrap metal chips, particularly brass and aluminum. Introduction of said metal chips into a molten mass of metal of which they are formed. Employment of metal salt flux for cleaning or purifying the metal chips and/or the molten mass of metal into which introduced. Maintaining rate of chip introduction at an optimum level. Apparatus for so doing.
2. Prior Art
With the value of metal chips, especially brass and aluminum chips, constantly on the increase, and with scrap metal chips now valued at between twenty and fifty cents per pound, the recovery and utilization of metal chips, but especially scrap metal chips, has become more and more advantageous from an economic standpoint. It is now possible to dry metal chips, including even extremely dirty scrap metal chips, by the employment of chip wringers of various types, such as the type manufactured by Reclamet and sold under that trademark, but in any event it is possible to clean metal chips chemically in the presence of a detergent and then vaporize excess water or to burn off the oil from chips thermally in a controlled combustion apparatus such as the rotary drum type. This provides essentially dry metal chips, which "dryness" is essential in view of the fact that metal chips cannot be introduced into a molten metal bath in a moisture-containing state without highly undesirable and even explosive reactions involving dissociation of the water and spontaneous combustion of the evolved hydrogen gas. However, although the economic aspects of recovering and utilizing metal chips has constantly improved, making their recovery and reuse more desirable, technology has not kept pace with such economic facts. As presently utilized in practice, the metal chips, particularly of the nonferrous type, after separation from ferrous or other magnetic-type chips and cleaning and demoisturizing, are still introduced into the charge well of a reverberatory furnace, or even into a channel-type induction furnace or a coreless-type induction furnace, in a manner which approaches the archaic. As a matter of fact, in present day practice for the introduction of metal chips into the molten metal pool in the charge well of a reverberatory furnace, the chips are simply thrown or otherwise deposited upon the surface of the molten metal, with accompanying disturbance of the metal oxide skin which normally exists atop the bath of molten metal, and allowed to settle into the said molten metal in the charge well or like equiment. Whether this is done in a batchwise or intermittent or continuous manner, the disturbance of the metal oxide skin atop the pool of molten metal is greatly disadvantageous and results in the agglomeration of much of the metal in the form of metal oxide as a part of said skin, rather than effectively causing the metal to melt in and become a part of the subterranean molten metal pool. In addition, when a metal salt flux of the usual type is employed for purposes of assisting with the cleaning of dirt and/or metal oxide from the molten metal, it is presently either sprinkled upon the chips or sprinkled upon the molten metal bath, at the top thereof, with very little efficiency due to the lack of intimate contact of the so-called "flux" with the metal chips being melted into the metal pool or with the relatively pure pool of molten metal itself. Further, no effective measures or apparatus are presently available for monitoring and controlling the rate of introduction of new metal into the pool at or near an optimum level. Nor has any suitable procedure or apparatus been developed for the alleviation of such inconvenient, timeconsuming, and inefficient method of operation, whereby metal chips, and especially scrap metal chips, may be reintroduced into the stream of commerce in the form of new metal, which of course requires at the outset that they be introduced into and become a part of a molten metal pool which in turn can be employed for all of the usual purposes and in all of the usual forming equipment, such as extruders, dies, and the like, where metal chips themselves are of course of no utility whatever.
The method and apparatus of the present invention provide long-awaited improvements in both the process and the apparatus for the utilization of metal chips involving the necessary step of introducing the same into a molten bath thereof at the commencement of their reentry into the stream of commerce.